Alloy



Patented Nov. 5, 1935 UNITED STATES PATENT OFFICE ALLOY James M. Lohr,Morristown, N. J., assignor to Driver-Harris Company, Harrison, N. .L, acorporat ion of New Jersey NojDrawing. Application June 14, 1935,

Serial No. 26,622

3 Claims.

5 oxidation at high temperatures is essential. The

alloys forming the subject matter of my invention are characterizedbythe ability to resist oxidation and by a prolonged life, exceedingthat of other known alloys, when used under high temperature conditions.

While nickel-chromium and nickel-chromiumiron alloys having the abilityto resist oxidation at high temperatures are known, their period ofusefulness in service is often not as long as de-. sired. I have foundthat the addition of small quantities of zirconium to suchnickel-chromium alloys greatly increases their period of life whenemployed under conditions where they are subjected to high temperatures.The alloys forming the subject matter of the present application mayalso contain small quantities of either sili-, con or manganese or bothof these elements.

In carrying out my invention I add small quantities of zirconium with orwithout silicon or manganese to nickel-chromium or nickel-chromium-ironalloys. The nickel-chromium alloy most generally used in the artconsists of 80 parts of nickel and 20 parts of chromium and I find itadvantageous to add the other metals mentioned above to nickel-chromiumalloys of substantially these proportions. The proportions of nickel andchromium in the alloy may be varied. Thus the chromium content may befrom 15 to 25 percent and the balance nickel.

Likewise the most generally used proportions of nickel, chromium andiron in nickel-chromium-iron alloys is 60 percent nickel, 10 to 15percent chromium and the balance iron and I find it advantageous in manycases to employ substantially these proportions of those ingredients,and add the zirconium. These proportions may also be varied, the nickel,however, forming the major part of the alloy, and the nickelchromiumcontent being such that the alloy will have the characteristics of anon-ferrous alloy.

I may employ from 7 to 22 percent chromium, 8 to 30 percent iron and thebalance nickel.

In preparing alloys containing zirconium, the quantities of it aresubtracted from the iron content, as for example, when zirconium isadded to an alloy containing 60 percent nickel, 10 to 15 percentchromium and the balance iron, the final alloy will contain 60 percentnickel, 10 to 15 percent chromium and zirconium in the percentagesherein stated and the balance iron.

The proportions of zirconium may vary within certain limits. I havefound that best results are obtained when this metal is present in thenickel-chromium or nickel-chromium-iron alloy within the followinglimits:

Percent .01-.50

If manganese or silicon are employed, they may be used within thefollowing limits:

Zirconium Percent 10 Manganese 0.02-2.0 Silir'nn 0.022.0

The preferred proportions of the alloying Nickel-chromium andnickel-chromium-iron .0

alloys containing zirconium within the proportions given have been foundby tests to have a greatly increased period of life when exposed to hightemperatures. For the purpose of determining the life of such alloys athigh temperatures I have tested them by the method of test outlined inTentative Accelerated Life Test for Metallic Materials for ElectricalHeating" of the American Society for Testing Materials described in vol,29 of the Proceedings of the Thirty- Second Annual Meeting of theAmerican Society for Testing Materials beginning on page 613. The methodis substantially as follows:

A sample of the wire to be tested, free from kinks, approximately twelveinches long and of about .025" diameter, is mounted vertically on thetest board, the upper end being held in position by means of a suitablebinding post. A 10 gram weight is attached to the lower end of thespecimen. A short piece of wire is attached to the 10 gram weight andprojects downward into a cup of mercury where it may move freely up anddown. A rheostat and an interrupter are connected in series with thespecimen to the power supply. The test is run on constant temperature ata standard temperature chosen for the alloy under consideration for thefirst twenty four hours. Thereafter it is run ori' constant voltage tothe burnout. a 10 percent increase in resistance is known as useful lifewhile the life to the burnout is known as total life. Throughout thetest the power is on two minutes and off two minutes. This isaccomplished by means of an interrupter. X

The life in hours up to 50 In testing the alloys of my inventionaccording to the above described method a reference sample composed of60 percent nickel, 15 percent chromium and percent iron and no alloyaddition having an approximate life of '70 hours was used. This value isconsidered as 100 percent and the useful life of the samples tested isdetermined in corresponding percentage values.

The addition of zirconium to such alloys within the limits set forthabove greatly increases the useful life where the wire is exposed to ahigh temperature as shown by the following example:

Percent useful um In the alloys referred toiherein, small amounts ofphosphorous and sulphur may be present as impurities. The nickel mayalso contain about 1 percent of cobalt.

I claim:

1. A nickel-chromium-iron alloy containing 7 to 22 percent chromium, 8to percent iron, .01 to percent zirconium, balance nickel.

2. A nickel-chromium-iron alloy containing 7 to 22 percent chromium, 8to 30 percent iron, substantially .25 percent zirconium, balance nickel.

3. A nickel-chromium-iron alloy containing 10 to 18 percent chromium, 17to 30 percent iron, .01 to .50 percent zirconium, balance nickel.

JAMES M. LOHR.

CERTIFICATE or CORRECTION.

Patent No. 2,019,688. November 5, 1935.

JAMES? M. LOHR.

lt is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,second column, line 8, claim 1, for "50" read .50; and that the saidLetters Patent should be read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this 10th day of December, A. D. 1935;

Leslie Frazer Acting Commissioner of Patents.

